Pretty young sport, this is a tough list to make. What the sport is now - GSP, Silva, Machida - is very, very different from what it was ten years ago - the Shamrocks, Gracie, even Ortiz. Back then fighter could excel at The One Thing and dominate people with it. Now, the champs are all well-rounded in all disciplines, and no one who isn't well-rounded really stands a chance (notable exception: Brock Lesnar.)